Previous studies investigating the effects of inhaled bronchodilators on sleep quality in COPD have shown conflicting results. These conflicting data prompted us to perform a retrospective study on patients with COPD and co-existing sleep apnea (OSA) investigating the effects of mechanical lung function impairment and lung hyperinflation on sleep. Our study found a significant correlation between increased lung hyperinflation and reduced sleep efficiency (a measure of sleep quality), and this relationship was preserved in a multivariable regression model.